Chapter 43

HOME-MIXING OF FERTILIZERS

The Practice of Home-mixing.--The business of compounding fertilizers has been involved in a great deal of unnecessary mystery. Many of our best station scientists have labored to show that the home-mixing of fertilizers is a simple and profitable piece of work, and the heaviest users of fertilizers in the east now buy unmixed materials, but a majority of farmers use the factory-mixed. Manufacturers are right in their contention that many people do not know what materials are best for their own fields, or what proportions are best, but the purchase of mixed materials does not solve their problem and it does not help them to a solution as quickly as home-mixing. The source of the plant-food in the factory-mixed goods is not known, while it is known in the home-mixed.

Effectiveness of Home-mixing.--Van Slyke says ("Fertilizers and Crops," p. 477): "Manufacturers of fertilizers and their agents have persistently sought to discourage the practice of home-mixing, but their statements cannot be accepted as the evidence of disinterested parties. It has been represented to farmers that peculiar and mysterious virtues are imparted to the plant-food constituents by proper mixing, and that really proper mixing can be accomplished only by means not at the command of farmers. Such statements are misrepresentations, based either upon the ignorance of the person who makes them or upon his determination to sell commercial mixed goods."

Criticisms of Home-mixing.--The manufacturer's advocate formerly laid much stress upon the danger attending the treatment of bones and rock with sulphuric acid. That is a business of itself, and the home-mixer has nothing to do with it. He buys on the market the acidulated bone or rock, just as a manufacturer makes his purchase.

It is claimed that the manufacturer renders a great public service by using supplies of plant-food that the home-mixer would not use, and thus conserves the world's total supply. Let us see the measure of truth in the statement. The manufacturer gets his supply of phosphoric acid from rock, bone, or tankage exactly as does the home-mixer. His potash he buys from the syndicate owning the German beds, and the farmer does the same. These sources must contribute all the phosphoric acid and potash used on land, if we except trifling supplies of ashes, marl, etc., and the only difference in the transaction is that in one case the manufacturer buys the materials and mixes them, and in the other case the farmer buys them direct and mixes them. The remaining constituent is the nitrogen. If the manufacturer uses nitrate of soda, sulphate of ammonia, bones, tankage, or manufactured nitrogen, he does what the home-mixer may do. Most nitrogen must come from these sources. If all came from these sources, the increased demand would not affect the price. The beds of nitrate of soda will last for hundreds of years, the present waste in ammonia from coal is immense, and the supply of manufactured nitrogen can be without limit. The saving in use of inert and low-grade forms of nitrogen is more profitable to the manufacturer than to the farmer who buys and pays freight on low-grade materials.

The rather remarkable argument is advanced that fertilizer manufacturers do not make a large per cent on their investment, despite the perfection of their equipment, and therefore the farmer cannot find it profitable to mix his materials at home. By the same reasoning, assuming for the moment that the profit in manufacturing does not pay a heavy dividend on all the stock issued, if a great hotel does not find its dining-room a source of profit, as many hotels do not, no private home should hope to prepare meals for its own members in competition with hotels.

As has been stated, every user of commercial fertilizer should learn what a pound of plant-food in unmixed material would cost him, selecting the common materials that are the only chief sources. If he can buy a pound of nitrogen in nitrate of soda or sulphate of ammonia, a pound of phosphoric acid in acid phosphate or steamed bone, and a pound of potash in muriate or sulphate of potash for less than they would cost in the factory-mixed goods offered him, allowing to himself a dollar or so a ton for the labor of mixing, it is only good business to buy the unmixed materials. The saving usually is from five to ten dollars a ton, excepting only interest on money, as he would pay cash for the unmixed material.

The cost of bags always is mentioned. That is not to be considered by the farmer, as he uses the bags in which the unmixed materials come to him.

The Filler.--There has been much misleading use of the word "filler," as applied to fertilizers. We have seen that a pure grade of dried blood contains about 13 per cent of nitrogen. The buyer of a ton of dried blood thus gets about 260 pounds of plant-food. The remaining 1740 pounds constitute what may be called nature's "filler." The blood is a good fertilizer. We do not buy nitrogen in a pure state. We buy a ton of material to get the needed 260 pounds of nitrogen. Thus it is with nitrate of soda, sulphate of ammonia, acid phosphate, muriate and sulphate of potash, and all other fertilizer materials. As freight must be paid upon the entire ton, it usually pays best to select materials that run high in percentage of plant-food. It is possible to get very low-grade fertilizers that have not had any foreign material added by the manufacturer. An acid phosphate may be poor in phosphoric acid because low-grade rock was used in its manufacture. Kainit is a low-grade potash because the impurities have not been taken out. Filler may be used, however, for two reasons, and one is legitimate. When limestone or similar material is used merely to add weight, reducing the value per ton, the practice is reprehensible. The extent of this practice is less than many suppose, preference being given to the use of low-grade materials in making very low-priced fertilizers.

A legitimate use of filler is to give good physical condition to a fertilizer. Some materials, such as nitrate of soda and muriate of potash, take up moisture and then become hard. The addition of peat or limestone or other absorbent is necessary to keep the mass in condition for drilling. The use of some steamed animal bone or high-grade tankage in the mixture helps to prevent caking. The home-mixer can use a drier without loss, as he does not pay freight upon it. Dry road dust will serve his purpose. His need of a drier may be greater than that of the manufacturer, as he probably will use only high-grade unmixed materials. If the use of the home-mixture is immediate, no drier to prevent caking is needed, but its presence facilitates drilling. Storage of unmixed materials in a dry place is an aid in maintaining good condition.

Ingredients in the Mixture.--The matters of interest to the farmer are the determination of the amounts of nitrogen, phosphoric acid, and potash that he should apply to a particular field, their availability, and their cost. Let us assume that he has found 300 pounds of a fertilizer containing 3 per cent nitrogen, 10 per cent phosphoric acid, and 6 per cent potash to be an excellent application for wheat on a thin soil that is to be seeded to clover and timothy. This fertilizer contains 3 pounds of nitrogen to each 100 pounds. He applies 300 pounds of the fertilizer per acre, or 9 pounds of nitrogen. The fertilizer contains 10 pounds of phosphoric acid to the 100 pounds. He thus applies 30 pounds of phosphoric acid per acre. The fertilizer contains 6 pounds of potash per 100 pounds, and he therefore applies 18 pounds per acre. What he has really learned, then, is that an acre of this land, when seeded to wheat, needs 9 pounds of nitrogen, 30 pounds of phosphoric acid, and 18 pounds of potash. It is in these terms he should do his thinking, and the matter of fertilization becomes simple.

In the general farming of the Pennsylvania experiment station, it is the practice to depend upon nitrate of soda as the source of a fertilizer for wheat. Manufacturers claim that sulphate of ammonia and tankage would be better. The farmer soon will learn what he prefers for his soil, provided he practices home-mixing.

Let us assume that he uses nitrate of soda, which never varies much from 15 per cent in its content of nitrogen. If 100 pounds of nitrate contain 15 pounds of nitrogen, the 9 pounds wanted for an acre will be found in 9/15 of 100 pounds or 60 pounds.

Thirty pounds of phosphoric acid are wanted for an acre. If the acid phosphate contains 14 per cent of phosphoric acid, or 14 pounds to the 100, the required amount will be 30/14 of 100, or 214 pounds.

Eighteen pounds of potash are wanted for an acre. The muriate of potash on our markets never varies much from 50 per cent in its content of potash. If 100 pounds of muriate contain 50 pounds of potash to the 100, the required amount wanted will be 18/50 of 100, or 36 pounds.

Adding the 60, 214, and 36 pounds, we have 310 pounds for the acre of land. If the field contains 20 acres, the order will call for 20 times the 60 pounds of nitrate of soda, 20 times the 214 pounds of acid phosphate, and 20 times the 36 pounds of potash.

If the farmer prefers to use sulphate of ammonia, which varies little from 20 per cent of nitrogen, or 20 pounds in the 100, he will get his 9 pounds of nitrogen for an acre by buying 9/20 of 100 pounds, or 45 pounds, and the substitution of the 45 pounds of sulphate of ammonia for the 60 pounds of nitrate of soda will reduce the total application of fertilizer per acre from 310 pounds to 295 pounds. The important fact is that in either case there is the required amount of nitrogen.

Let us assume that the field contains enough nitrogen, but other needs remain the same. In such case, the nitrogen is dropped out, and the application becomes 250 pounds per acre.

The home-mixer may substitute tankage of guaranteed analysis for part of the nitrogen and phosphoric acid. Let us assume that the tankage runs 9 per cent nitrogen and 20 per cent phosphoric acid. If half the required nitrogen per acre, or 4-1/2 pounds, is wanted in tankage, 50 pounds of the tankage will supply it. At the same time the 50 pounds of tankage supplies 10 pounds of phosphoric acid, replacing one third of the 214 pounds of acid phosphate. We thus have for the acre 30 pounds of nitrate of soda, 50 pounds of tankage, 143 pounds of acid phosphate, and 36 pounds of potash, or 259 pounds. The content of plant-food remains the same, but one half of the nitrogen is only slowly available. The farmer who buys unmixed materials will incline to use only a few kinds, and at first he will confine himself chiefly to materials whose composition varies little. In this way he quickly sees in a ton of the material, not the whole bulk, but the definite number of pounds of nitrogen and other constituents of plant-food contained in it, and the calculations in home-mixing become simple.

Materials that should not be Combined.--The advocate of factory-mixed goods warns the farmer against the danger of making combinations of materials that will cause loss by chemical action. The danger is wholly imaginary if no form of lime, wood-ashes, or basic slag is used in the home-mixtures. As has been said, some materials will harden, if permitted to absorb moisture, and if the mixture must stand, a few hundred pounds of muck or dry road dust should be added to each ton as a drier, and a correspondingly larger amount per acre should be applied.

Making a Good Mixture.--The process of mixing is simple, and careful station tests have shown that it is fully as effective as factory-mixing. The unmixed materials should be kept in a dry place until the mixing is done. If there are any coarse lumps, a wooden tamper can crush them on the barn floor, and the material should be passed through a sand-screen. The material of largest bulk should be spread on the floor, and the other materials should be put on in layers. Three careful turnings with a shovel will secure good mixing. Scales should be used to secure accuracy in desired amounts of the materials.

Buying Unmixed Materials.--Acid phosphate, animal bone, and tankage can be bought of any fertilizer agent, but when one pays cash, he does well to get quotations from various leading manufacturers. The names of dealers in nitrate of soda can be secured from the New York agency which keeps its address before the public in agricultural papers. This is likewise true in the case of the syndicate controlling all the potash. When the addresses of leading distributors of all needed materials have been secured, quotations should be obtained on a cash basis. The best terms are obtained by groups of men combining their orders.